Flame retardant plastic resin composition

ABSTRACT

The invention relates to a flame-retardant thermoplastic resin composition having incorporated therein a trace of stabilized red phosphorus, which achieves both improvement of heat resistance and flame retardation without using chlorine nor bromine and also possesses long-term heat stability and smells little. The composition comprises (A) 50 to 95 parts by weight of a polycarbonate resin and (B) 5 to 50 parts by weight of a thermoplastic polyester resin, contains (C) 0.1 to 5 parts by weight, per 100 parts by weight of the total amount of (A) and (B), of coated stabilized red phosphorus and preferably contains (D) 0.1 to 100 parts by weight, per 100 parts by weight of the total amount of (A) and (B), of a silicate compound.

TECHNICAL FIELD

[0001] This invention relates to a flame-retardant thermoplastic resincomposition. More particularly, it relates to a flame-retardantthermoplastic resin composition having incorporated therein a trace ofstabilized red phosphorus, which achieves both improvement of heatresistance and flame retardation without using chlorine nor bromine andalso possesses long-term heat stability and smells little.

BACKGROUND ART

[0002] Polycarbonate resins are thermoplastic resins having excellentimpact resistance and heat resistance and widely used as parts in thefields of machinery, automobiles, electricity and electronics. Inparticular aromatic polycarbonate resins have a high glass transitiontemperature and are expected to exhibit high heat stability. However,they frequently fail to show sufficient flowability in processing.Therefore, aromatic polycarbonate resins should be processed atrelatively high processing temperatures around 300° C. In moldingaromatic polycarbonate resins by, for example, injection molding,relatively high injection speed and pressure are required.

[0003] On the other hand, thermoplastic polyester resins are excellentin mechanical properties, electrical properties, and chemical resistanceand exhibit satisfactory flowability on being heated at or above theircrystal melting point and therefore have been used widely as fiber, filmand a molding material.

[0004] It has been attempted to improve the flowability and the like ofpolycarbonate resins by taking advantage of these characteristics of thethermoplastic polyester resin. For example, JP-B-36-14035 (the term“JP-B” as used herein means an “examined published Japanese patentapplication”), JP-B-39-20434, and JP-A-59-176345 (the term “JP-A” asused herein means an “unexamined published Japanese patent application”)propose a polycarbonate resin composition containing a polyester resin,such as polyethylene terephthalate, polybutylene terephthalate, etc.

[0005] In order to secure safety against fire, thermoplastic resins areoften required to have such flame retardance as to meet the standards ofUL-94 V-0 or 5V (Underwriter's Laboratories Standard, U.S.A.). Variousflame retardants have been developed and studied for this purpose.

[0006] Recent environmental concerns growing particularly in Europe havepromoted the study on the use of halogen-free flame retardants, such asphosphorus type flame retardants. Useful phosphorus type flameretardants include organic phosphorous compounds and red phosphorus.

[0007] Known organic phosphorus compounds include those disclosed inJP-A-63-227632, JP-A-5-1079, and JP-A-5-279513. Compositions which aremade flame-retardant by addition of an organic phosphorus flameretardant include the flame-retardant resin composition ofJP-A-5-179123, which comprises a polycarbonate resin and other resinsand contains an organic phosphorus flame retardant, a boron compound,organopolysiloxane, and a fluororesin, and the flame-retardant resincomposition of JP-A-6-192553, which comprises a polycarbonate resin anda polyalkylene terephthalate resin and contains a graft copolymer, anoligomeric organic phosphorus flame retardant, and a fluorinatedpolyolefin.

[0008] Known red phosphorous species include those described inJP-B-54-39200, JP-A-55-10463, and JP-B-5-8125. Compositions which aremade flame-retardant with red phosphorus include flame-retardant resincompositions comprising a polycarbonate resin and powdered redphosphorus as disclosed in JP-A-48-85642 and JP-A-50-78651.

[0009] Red phosphorus is difficult to handle because for one thing it isa dangerous chemical having a danger of dust explosion and for anotherit tends to emit smell or gas when processed in high temperature. Inorder to overcome these problems, various techniques for coating thesurface of red phosphorus for stabilization have been proposed. Forexample, JP-A-52-142751, JP-B-5-18356, and JP-A-5-239260 disclose redphosphorus coated with a thermosetting resin, aluminum hydroxide, etc.or electrolessly plated red phosphorus and thermoplastic resins whichare rendered flame-retardant by addition of the thus stabilized redphosphorus.

[0010] JP-B-2-37370 proposes a flame-retardant resin compositioncomprising a polyester resin and thermosetting resin-coated redphosphorus and, if desired, a reinforcing filler. JP-A-5-239260 andJP-A-5-247264 disclose a flame-retardant resin composition comprising athermoplastic resin such as a polycarbonate alloy, a polyester resin,etc. and electrolessly plated red phosphorus.

[0011] In the fields where such flame-retardant resin compositions areused as, for example, electric and electronic parts, simplification ofassembly and cost reduction have been desired, and it has been promotedto make parts integral-or thinner. Therefore, materials used in theseparts are required to show satisfactory flowability in molding and tomaintain high heat resistance and high flame retardance.

[0012] However, addition of an organic phosphorus flame retardant to apolycarbonate resin in an attempt to impart sufficient flame retardanceresults in considerable reduction in heat resistance.

[0013] Polycarbonate resin compositions containing red phosphorus orstabilized red phosphorus lack long-term heat stability. That is,moldings obtained suffer from deformation when exposed to a temperatureno higher than around 150° C. for a long time. Besides, the compositionshave poor molding processability because of low flowability. If thecompositions are molded at high temperatures to secure flowability,there arise different problems such that a smell attributable to redphosphorus issues during molding and that decomposition gas generatesduring molding to contaminate the mold.

[0014] In addition it is difficult with red phosphorus alone to obtainsufficient flame retardance. It means that red phosphorus should be usedeither in a large quantity or in combination with another flameretardant or a flame retardation aid. However, addition of a largequantity of red phosphorus leads to a stronger smell attributable to redphosphorus, and a combined use of a flame retardation aid results in notonly destruction of the balance of properties of the resin but anincrease of cost.

DISCLOSURE OF INVENTION

[0015] The inventors have conducted extensive investigation on redphosphorus-containing flame-retardant resin compositions. As a result,they have surprisingly found that improvements in heat resistance andlong-term heat stability result when stabilized red phosphorus is addedto an alloy comprising a polycarbonate resin and a polyester resin ascompared with the alloy containing no stabilized red phosphorus and thatthis effect is never be observed with other thermoplastic resins. Theyhave ascertained that addition of only a trace amount of stabilized redphosphorus to a polycarbonate resin-polyester resin alloy produces highflame retardance to provide a flame-retardant resin composition thatretains the excellent characteristics possessed by the alloy, such asmolding processability, non-smelling properties, and the like. They haveadditionally discovered that addition of a combination of stabilized redphosphorus and a silicate compound brings about further improvements innot only flame retardance but the above-mentioned other properties. Thepresent invention has been reached based on these findings.

[0016] The present invention provides in its first aspect aflame-retardant thermoplastic resin composition comprising (A) 50 to 95parts by weight of a polycarbonate resin, (B) 5 to 50 parts by weight ofa thermoplastic polyester resin and (C) 0.1 to 5 parts by weight, per100 parts by weight of the total of (A) and (B), of coated stabilizedred phosphorus.

[0017] The present invention provides in its second aspect aflame-retardant thermoplastic resin composition comprising (A) 50 to 95parts by weight of a polycarbonate resin, (B) 5 to 50 parts by weight ofa thermoplastic polyester resin and (C) 0.1 to 5 parts by weight, per100 parts by weight of the total amount of (A) and (B), of coatedstabilized red phosphorus and (D) 0.1 to 100 parts by weight, per 100parts by weight of the total amount of (A) and (B), of a silicatecompound.

[0018] The resin composition of the invention can further contain one ormore of components (E) to (G) hereinafter described.

[0019] In a preferred embodiment of the invention, the flame-retardantthermoplastic resin composition further contains (E) 0.01 to 5 parts byweight of a fluorocarbon resin and/or silicone per 100 parts by weightof the total amount of (A) and (B).

[0020] In a preferred embodiment of the invention, the flame-retardantresin composition contains (C) 0.1 to 3 parts by weight of stabilizedred phosphorus, (D) 0.1 to 100 parts by weight of a silicate compound,and (E) 0.01 to 5 parts of a fluorocarbon resin and/or silicone, eachper 100 parts by weight of the-total amount of (A) and (B).

[0021] In another preferred embodiment of the invention, theflame-retardant resin composition further contains (F) 0.1 to 30 partsby weight of an organic phosphorus flame retardant per 100 parts byweight of the total amount of (A) and (B).

[0022] In still another preferred embodiment of the invention, theflame-retardant resin composition further contains (G) 0.1 to 20 partsby weight of at least one elastic resin selected from graft polymers andolefin resins per 100 parts by weight of the total amount of (A) and(B).

[0023] In yet another preferred embodiment of the invention, thethermoplastic polyester resin as component (B) is a polyalkyleneterephthalate having not less than 80% by weight of an alkyleneterephthalate unit.

[0024] In an additional preferred embodiment of the invention, thestabilized red phosphorus flame retardant as component (C) is redphosphorus coated with at least one substance selected from athermosetting resin, a metal hydroxide, and a plating metal.

[0025] Polycarbonate resin (A) used in the present invention is obtainedby reacting a di- or polyhydric phenol compound and phosgene or acarbonic diester such as diphenyl carbonate.

[0026] There are various dihydric phenols usable. Particularly suitableis 2,2-bis(4-hydroxyphenyl)propane, which is generally called bisphenolA. Dihydric phenols other than bisphenol A includedihydroxydiarylalkanes, such as bis(4-hydroxyphenyl)methane,bis(4-hydroxyphenyl)phenylmethane, bis(4-hydroxyphenyl)naphthylmethane,bis(4-hydroxyphenyl)-(4-isopropylphenyl)methane,bis(3,5-dimethyl-4-hydroxyphenyl)methane,1,1-bis(4-hydroxyphenyl)ethane,1-naphthyl-1,1-bis(4-hydroxyphenyl)ethane,1-phenyl-1,1-bis(4-hydroxyphenyl)ethane, 1,2-bis(4-hydroxyphenyl)ethane,2-methyl-1,1-bis(4-hydroxyphenyl)propane,2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane,1-ethyl-1,1-bis(4-hydroxyphenyl)propane,2,2-bis(3-methyl-4-hydroxyphenyl)propane,1,1-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)butane,1,4-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)pentane,4-methyl-2,2-bis(4-hydroxyphenyl)pentane,2,2-bis(4-hydroxyphenyl)hexane, 4,4-bis(4-hydroxyphenyl)heptane,2,2-bis(4-hydroxyphenyl)nonane, 1,10-bis(4-hydroxyphenyl)decane, and1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane;dihydroxydiarylcycloalkanes, such as 1,1-bis(4-hydroxyphenyl)cyclohexaneand 1,1-bis(4-hydroxyphenyl)cyclodecane; dihydroxydiarylsulfones, suchas bis(4-hydroxyphenyl)sulfone andbis(3,5-dimethyl-4-hydroxyphenyl)sulfone; dihydroxydiaryl ethers, suchas bis(4-hydroxyphenyl) ether and bis(3,5-dimethyl-4-hydroxyphenyl)ether; dihydroxydiaryl ketones, such as 4,4′ -dihydroxybenzophenone and3,3′,5,5′-tetramethyl-4,4′-dihydroxybenzophenone; dihydroxydiarylsulfides, such as bis(4-hydroxyphenyl) sulfide,bis(3-methyl-4-hydroxyphenyl) sulfide, andbis(3,5-dimethyl-4-hydroxyphenyl) sulfide; dihydroxydiaryl sulfoxides,such as bis(4-hydroxyphenyl) sulfoxide; dihydroxydiphenyls, such as 4,4′-dihydroxydiphenyl; and dihydroxyarylfluorenes, such as9,9-bis(4-hydroxyphenyl)fluorene. In addition to the dihydric phenols,dihydroxybenzenes, such as hydroquinone, resorcinol, andmethylhydroquinone; and dihydroxynaphthalenes, such as1,5-dihydroxynaphthalene and 2,6-dihydroxynaphthalene, are also useful.These dihydric phenols can be used either individually or as acombination of two or more thereof.

[0027] Suitable carbonic diester compounds include diaryl carbonates,such as diphenyl carbonate, and dialkyl carbonates, such as dimethylcarbonate and diethyl carbonate.

[0028] The polycarbonate resin as component (A) can contain a branchedpolycarbonate if desired. Branching agents which can be used forobtaining branched polycarbonates include phloroglucin, mellitic acid,trimellitic acid, trimellitic chloride, trimellitic anhydride, gallicacid, n-propyl gallate, protocatechuic acid, pyromellitic acid,pyromellitic acid dianhydride, α-resorcylic acid, β-resorcylic acid,resorcylaldehyde, isatinbis(o-cresol), benzophenonetetracarboxylic acid,2,4,4′ -trihydroxybenzophenone, 2,2′,4,4′-tetrahydroxybenzophenone,2,4,4′-trihydroxyphenyl ether, 2,2′,4,4′-tetrahydroxyphenyl ether,2,4,4′-trihydroxydiphenyl-2-propane,2,2′-bis(2,4-dihydroxyphenyl)propane, 2,2′,4,4′-tetrahydroxydiphenylmethane, 2,4,4′ -trihydroxydiphenylmethane,1-[α-methyl-α-(4′ -dihydroxyphenyl)ethyl]-3-[α′,α′-bis(4″-hydroxyphenyl)ethyl]benzene, 1-[α-methyl-α-(4′-dihydroxyphenyl)ethyl]-4-[α′α′-bis(4″ -hydroxyphenyl)ethyl]benzene,α,α′,α″-tris(4-hydroxyphenyl)-1,3,5-triisopropylbenzene,2,6-bis(2-hydroxy-5′ -methylbenzyl)-4-methylphenol,4,6-dimethyl-2,4,6-tris(4′ -hydroxyphenyl)-heptene,4,6-dimethyl-2,4,6-tris(4′ -hydroxyphenyl)-heptane,1,3,5-tris(4′-hydroxyphenyl)benzene, 1,1,1-tris(4-hydroxyphenyl)ethane,2,2-bis[4,4-bis(4′ -hydroxyphenyl)cyclohexyl]propane,2,6-bis(2′-hydroxy-5′-isopropylbenzyl)-4-isopropylphenol,bis[2-hydroxy-3-(2′ -hydroxy-5′-methylbenzyl)-5-methylphenyl]methane,bis[2-hydroxy-3-(2′-hydroxy-5′-isopropylbenzyl)-5-methylphenyl]methane,tetrakis(4-hydroxyphenyl)methane, tris(4-hydroxyphenyl)phenylmethane,2′,4′,7-trihydroxyflavan, 2,4,4-trimethyl-2′,4′,7-trihydroxyflavan,1,3-bis(2′,4′ -dihydroxyphenylisopropyl)benzene, and tris(4′-hydroxyphenyl)-amyl-s-triazine.

[0029] In some cases, a polycarbonate-polyorganosiloxane copolymercomposed of a polycarbonate segment and an polyorganosiloxane segmentcan be used as polycarbonate resin (A). The degree of polymerization ofthe polyorganosiloxane segment is preferably 5 or more.

[0030] Additionally, polycarbonate resins comprising a comonomer unitderived from a straight-chain aliphatic dicarboxylic acid, such asadipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, anddecanedicarboxylic acid, can also be used as component (A).

[0031] Various known polymerization terminators can be used in producingthe polycarbonate resin. Suitable terminators include monohydricphenols, such as phenol, p-cresol, p-t-butylphenol, p-t-octylphenol,p-cumylphenol, and nonylphenol.

[0032] For the purpose of increasing flame retardance, copolymerscomprising a phosphorus compound unit or phosphorus compound-terminatedpolymers can be used. For improving weather resistance, copolymerscomprising a dihydric phenol unit having a benzotriazole group can beused.

[0033] Polycarbonate resin (A) which can be used in the presentinvention preferably has a viscosity average molecular weight of 10000to 60000, still preferably 15000 to 45000, particularly preferably 18000to 35000. If the viscosity average molecular weight is less than 10000,the resulting resin composition tends to have insufficient strength orheat resistance. If it exceeds 60000, the composition tends to haveinsufficient molding processability.

[0034] These polycarbonate resins can be used either individually or asa combination of two or more thereof. The combination of thepolycarbonate resins is not limited. For example, two or more resinsdifferent in monomer unit, copolymerizing molar ratio and/or molecularweight can be combined arbitrarily.

[0035] Thermoplastic polyester resin (B) is a resin obtained bypolycondensation of a di- or polycarboxylic acid component, a di- orpolyhydric alcohol and/or phenol component in a known manner. Examplesof useful thermoplastic polyester resins are polyethylene terephthalate,polypropylene terephthalate, polybutylene terephthalate,polyhexamethylene terephthalate, polycyclohexanedimethyleneterephthalate, polyethylene naphthalate, and polybutylene naphthalate.

[0036] Of the di- or polycarboxylic acid components, aromaticpolycarboxylic acid components having 8 to 22 carbon atoms andester-forming derivatives thereof are used. Examples thereof includephthalic acids, such as terephthalic acid and isophthalic acid;carboxylic acids, such as naphthalenedicarboxylic acid,bis(p-carboxyphenyl)methane, anthracenedicarboxylic acid,4,4′-diphenyldicarboxylic acid, 1,2-bis(phenoxy)ethane-4,4′-dicarboxylicacid, diphenylsulfonedicarboxylic acid, trimesic acid, trimellitic acid,and pyromellitic acid; and ester-forming derivatives thereof. They canbe used either individually or as a combination of two or more thereof.Preferred of them are terephthalic acid, isophthalic acid, andnaphthalenedicarboxylic acid for their ease of handling and reacting andexcellent physical properties of the resulting resin.

[0037] Other useful di- or polycarboxylic acid components includealiphatic ones having 4 to 12 carbon atoms, alicyclic ones having 8 to15 carbon atoms, and ester-forming derivatives thereof. Examples areadipic acid, sebacic acid, azelaic acid, dodecanedicarboxylic acid,maleic acid, 1,3-cyclohexanedicarboxylic acid, and1,4-cyclohexanedicarboxylic acid, and ester-forming derivatives thereof.

[0038] The ester-forming derivatives of the carboxylic acids arederivatives capable of forming an ester, such as carboxylic acid halides(e.g., carboxylic acid chloride) and carboxylic acid esters.

[0039] The di- or polyhydric alcohol and/or phenol component includesaliphatic compounds having 2 to 15 carbon atoms, alicyclic compoundshaving 6 to 20 carbon atoms and aromatic compounds having 6 to 40 carbonatoms, each of which having two or more hydroxyl groups per molecule,and ester-forming derivatives thereof. Examples of such alcoholic and/orphenolic components include ethylene glycol, propylene glycol,butanediol, hexanediol, decanediol, neopentyl glycol,cyclohexanedimethanol, cyclohexanediol,2,2′-bis(4-hydroxyphenyl)propane, 2,2′-bis(4-hydroxycyclohexyl)propane,hydroquinone, glycerol, and pentaerythritol, and their ester-formingderivatives. Preferred alcohol and/or phenol components are ethyleneglycol, butanediol, and cyclohexanedimethanol for their ease of handlingand reacting and excellent physical properties of the resulting resin.

[0040] Thermoplastic polyester resin (B) may further comprise knowncopolymerizable component in addition to the above-mentioned acidcomponent and alcohol and/or phenol component as far as thecharacteristics as desired are not impaired.

[0041] Oxyacids, such as p-hydroxybenzoic acid, and their ester-formingderivatives, cyclic esters, such as ε -caprolactone, and the like canalso be used as a copolymerizable component.

[0042] Further, copolymers having copolymerized in the polymeric chain apolyalkylene glycol unit, such as polyethylene glycol, polypropyleneglycol, poly(ethylene oxide-propylene oxide) block and/or randomcopolymers, ethylene oxide-added bisphenol A copolymers, propyleneoxide-added bisphenol A copolymers, tetrahydrofuran-added bisphenol Acopolymers, and polytetramethylene glycol, can also be used. Theproportion of these copolymer unit is generally 20% by weight or less,preferably 15% by weight or less, particularly 10% by weight or less.

[0043] It is preferred that thermoplastic polyester resin (B) be apolyalkylene terephthalate, preferably one having an alkyleneterephthalate unit content of 80% by weight or more, particularly -85%by weight or more, especially 90% by weight or more. Such a polyalkyleneterephthalate provides a resin composition having well-balanced physicalproperties, such as moldability.

[0044] It is preferred for thermoplastic polyester resin (B) to have anintrinsic viscosity (IV) of 0.30 to 2.00 dl/g, still preferably 0.40 to1.80 dl/g, particularly preferably 0.50 to 1.60 dl/g, as measured in aphenol/tetrachloroethane (1/1 by weight) mixed solvent at 25° C. If theintrinsic viscosity is less than 0.30 dl/g, the resulting moldings tendto have insufficient flame retardance or mechanical strength. If itexceeds 2.00 dl/g, the composition tends to have reduced flowability inmolding.

[0045] The thermoplastic polyester resins as component (B) can be usedeither individually or as a combination of two or more thereof. Thecombination is not limited. For example, two or more resins different inmonomer unit, copolymerizing molar ratio and/or molecular weight can becombined arbitrarily.

[0046] The mixing ratio of polycarbonate resin (A) and thermoplasticpolyester resin (B) is from 95/5 to 50/50, preferably 90/10 to 55/45,still preferably 85/15 to 60/40, by weight. If the weight ratio ofthermoplastic polyester resin (B) in the (A)/(B) mixture is less than 5,the resulting resin composition has insufficient molding flowability,and the effect of stabilized red phosphorus in improving long-term heatstability is insubstantial. If it exceeds 50, the impact resistance thatis characteristic of polycarbonate resins is reduced.

[0047] Stabilized red phosphorus (C) is red phosphorus having beenstabilized by surface coating through various methods. Red phosphoruscoated with at least one substance selected from a thermosetting resin,a metal hydroxide, and a plating metal is preferred. Any thermosettingresin that can coat red phosphorus can be used without particularlimitation. Suitable thermosetting resins include a phenol-formalinresin, a urea-formalin resin, a melamine-formalin resin, and an alkydresin. Any metal hydroxide that can coat red phosphorus can be used withno particular limitation. Suitable metal hydroxides include aluminumhydroxide, magnesium hydroxide, zinc hydroxide, and titanium hydroxide.Any electrolessly plating film that can coat red phosphorus can be usedwith no particular limitation. Examples of the plating metals includeFe, Ni, Co, Cu, Zn, Mn, Ti, Zr, Al, and their alloys. Two or more ofthese coating substances can be used as a mixture or can be provided indifferent layers.

[0048] The coated and stabilized red phosphorus is advantageous for itsease of handling and improved smell.

[0049] The stabilized red phosphorus species can be used eitherindividually or as a combination of two or more thereof. The combinationis not limited. For example, species different in kind of the coatingsubstance and/or particle size can be combined arbitrarily.

[0050] The content of stabilized red phosphorus (C) is 0.1 to 5 parts byweight, preferably 0.3 to 4 parts by weight, still preferably 0.5 to 3parts by weight, per 100 parts by weight of the total of polycarbonateresin (A) and thermoplastic polyester resin (B). If it is less than 0.1part, the resulting molded articles have insufficient flame retardance.If it exceeds 5 parts, the resin composition gives off smell vigorously.

[0051] It is preferable for the flame-retardant thermoplastic resincomposition of the invention to contain a silicate compound as component(D). The existence of a silicate, even in a trace amount, brings aboutsignificant improvement in flame retardance. Addition of a silicatecompound also leads to improvements in heat resistance and elasticmodulus. Useful silicate compounds typically include those containing achemical composition of an SiO₂ unit. While not limiting, the silicatecompound usually has a particulate shape, a granular shape, aneedle-like shape, a tabular shape, etc. The silicate compound to beused may be either a natural one or a synthetic one.

[0052] Specific examples of suitable silicate compounds are magnesiumsilicate, aluminum silicate, calcium silicate, talc, mica, wollastonite,kaolin, diatomaceous earth, and smectite. Preferred are mica, talc,kaolin and smectite because they are highly effective in not onlygreatly enhancing flame retardance but suppressing anisotropy of moldedarticles and improving heat resistance and mechanical strength.

[0053] Mica as component (D) is not particularly limited in species. Anarbitrary choice can be made from among commonmica (muscovite),phlogopite, sericite, biotite, paragonite, synthetic mica, and the like.The mica can be surface-treated to have improved adhesion to the resinmatrix. A silane coupling agent containing an epoxy group, such asepoxysilane, is a preferred surface treating agent; for it will notreduce the physical properties of the resins. The surface treatment canbe carried out in a conventional manner with no particular restriction.

[0054] It is preferred that the mica to be used has a weight-averageflake diameter of 1 to 40 μm for the reasons that: the effects in flameretardation and prevention of dripping are enhanced; the processabilityin melt kneading is improved; and the resulting molded articles haveimproved impact strength. It is still preferred for the mica to have aweight-average flake diameter of 2 to 37 μm, particularly 3 to 35 μm. Ifthe weight-average flake diameter is smaller than 1 μm, the particlesare difficult to melt-knead together with resinous components because oftheir too high bulk specific gravity. If the weight-average flakediameter is greater than 40 μm, the impact resistance of molded articlesand the dripping prevention effect tend to be reduced.

[0055] The terminology “weight-average flake diameter” as used hereinfor mica denotes the size of the opening of a microsieve through which50% by weight of particles pass in the plots on a Rosin-Rammlardistribution, which is prepared by classifying the particles withmicrosieves of various opening sizes.

[0056] These mica species can be used either individually or as amixture of two or more thereof different in particle size, kind, surfacetreating agent, and the like.

[0057] In using talc as component (D), it is preferred to use talchaving a weight-average particle diameter of 1.0 μm or more and a bulkspecific volume of 8.0 ml/g or less for obtaining enhanced effects ofaddition in flame retardation and dripping prevention, improvedprocessability in melt kneading, and improved impact strength of moldedarticles. The weight-average particle diameter is still preferably 1.1to 30 μm, particularly 1.2 to 20 μm. The bulk specific volume is stillpreferably 7.0 ml/g or less, particularly 6.0 ml/g or less. Talc havinga weight-average particle diameter of less than 1.0 μm or a bulkspecific volume exceeding 8.0 ml/g is difficult to melt-knead withresinous components and tends to produce only a poor effect inpreventing resin dripping. If the weight-average particle size exceeds30 μm, the molded article tends to have reduced impact strength.

[0058] The terminology “weight-average particle diameter” as used hereinfor talc means the size of the opening of a microsieve through which 50%by weight of particles pass when the particles are classified withmicrosieves of various opening sizes.

[0059] The talc to be used in the present invention is chosenappropriately from commercially available products without particularlimitation in kind, place of origin, etc. The talc can besurface-treated to have improved adhesion to the resin matrix. A silanecoupling agent containing an epoxy group, such as epoxysilane, is apreferred surface treating agent, for it will not reduce the physicalproperties of the resins. The surface treatment can be carried out in aconventional manner with no particular restriction. These talc speciescan be used either individually or as a mixture of two or more speciesdifferent in particle diameter, kind, surface treating agent, etc.

[0060] Silicate compound (D) is added in an amount of 0.1 to 100 partsby weight, preferably 0.2 to 70 parts by weight, still preferably 0.3 to50 parts by weight, per 100 parts by weight of the total amount ofpolycarbonate resin (A) and aromatic polyester resin (B). Less than 0.1part by weight of silicate compound (D) tends to produce poor effect inimproving flame retardance, heat resistance and mechanical strength ofmolded articles. More than 100 parts by weight of silicate compound (D)tends to reduce the impact resistance and surface properties of moldedarticles and to be difficult to melt-knead with the resins.

[0061] For the purpose of further improving flame retardance, (E) afluorocarbon resin and/or silicone can be used in the present invention.

[0062] The fluorocarbon resin is a resin containing a fluorine atom andincludes polymonofluoroethylene, polydifluoroethylene,polytrifluoroethylene, polytetrafluoroethylene, and atetrafluoroethylene-hexafluoropropylene copolymer. If desired,copolymers obtained from a monomer which provides the above-describedfluorocarbon resin and a copolymerizable monomer can be used in such anamount that will not ruin the physical properties of resulting moldedarticles such as flame retardance. These fluorocarbon resins can be usedeither individually or as a combination of two or more thereof.

[0063] The fluorine content in the fluorocarbon resin is preferably suchthat corresponds to polymono- to tetrafluoroethylene.Polytetrafluoroethylene is preferred the most of the fluorocarbonresins.

[0064] The fluorocarbon resin preferably has a molecular weight of1,000,000 to 20,000,000, particularly 2,000,000 to 10,000,000. Thefluorocarbon resin can be prepared by customary methods, such asemulsion polymerization, suspension polymerization, bulk polymerization,and solution polymerization.

[0065] The silicone is an organosiloxane, including siloxane compounds,e.g., dimethylsiloxane and phenylmethylsiloxane, and polyorganosiloxanesobtained by homo- or copolymerizing the siloxane compounds, such asdimethyl polysiloxane, phenylmethyl polysiloxane. The polyorganosiloxanemay be modified silicone having its molecular end substituted with anepoxy group, a hydroxyl group, a carboxyl group, a mercapto group, anamino group, an ether group, etc.

[0066] Inter alia, polymers having a number average molecular weight of200 or higher, particularly 1,000 to 5,000,000, are preferred for theireffect in improving flame retardance. The silicone is not particularlylimited in form and can have any of an oil form, a rubber form, avarnish form, a powder form, a pellet form, etc.

[0067] Fluorocarbon resin and/or silicone (E) is/are added in an amountof 0.01 to 5 parts by weight, preferably 0.03 to 4 parts by weight,still preferably 0.05 to 3.5 parts by weight, per 100 parts by weight ofthe total amount of polycarbonate resin (A) and thermoplastic polyesterresin (B). If the amount is less than 0.01 part, the effect in improvingflame retardance is small. If it exceeds 5 parts, the moldability isreduced.

[0068] Where silicate compound (D) and fluorocarbon resin and/orsilicone (E) are added in combination, there is produced an increasedflame retardation effect so that satisfactory flame retardance can beobtained even with the amount of stabilized red phosphorus (C) being assmall as 0.1 to 3 parts by weight. As a result, the smell on molding isfurther weakened, and the cost of production is reduced. The amount ofstabilized red phosphorus (C) to be added is preferably 0.2 to 2.8 partsby weight, still preferably 0.3 to 2.5 parts.

[0069] In the present invention, the flame retardance and moldingprocessability can further be improved by adding (F) an organicphosphorus flame retardant according to the end use and purpose. Usefulorganic phosphorus flame retardants include phosphates, phosphonates,phosphinates, phosphine oxides, phosphites, phosphonites, phosphinitesand phosphines. Specific examples are trimethyl phosphate, triethylphosphate, tributyl phosphate, tri(2-ethylhexyl) phosphate,tributoxyethyl phosphate, triphenyl phosphate, tricresyl phosphate,trixylenyl phosphate, tris(isopropylphenyl) phosphate,tris(phenylphenyl) phosphate, trinaphthyl phosphate, cresyldiphenylphosphate, xylenyldiphenyl phosphate, diphenyl(2-ethylhexyl) phosphate,di(isopropylphenyl)phenyl phosphate, phenyldicresyl phosphate,di-2-ethylhexyl phosphate, monoisodecyl phosphate, 2-acryloyloxyethylacid phosphate, 2-methacryloylxyethyl acid phosphate,diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethylphosphate, triphenyl phosphite, trisnonylphenyl phosphite, tristridecylphosphite, dibutyl hydrogenphosphite, triphenylphosphine oxide,tricresylphosphine oxide, diphenyl methanephosphonate, and diethylphenylphosphonate.

[0070] In particular, phosphoric esters represented by formula:

[0071] wherein R¹, R², R³, and R⁴ each represent a monovalent aromaticor aliphatic group; R⁵ represents a divalent aromatic group; nrepresents a number of from 0 to 16; nR³'s and nR⁵'s may be the same ordifferent, respectively, are preferred for their excellent flameretardation effect and ease of handling. Condensed phosphoric esters ofthe above formula, in which n is 1 to 16, are still preferred; for theycause less contamination of the metallic part of a mold.

[0072] Examples of the phosphoric esters of the above formula wherein nis 0 are triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate,cresyldiphenyl phosphate, and xylenyldiphenyl phosphate.

[0073] Examples of the condensed phosphoric esters of the above formulaare shown below.

[0074] (1) Resorcinolbis(diphenyl) phosphate

[0075] (2) Resorcinolbis(di-2,6-xylyl) phosphate

[0076] (3) Bisphenol A bis(dicresyl) phosphate

[0077] (b 4) Hydroquinonebis(di-2,6-xylyl) phosphate

[0078] (5) Condensates comprising these phosphates.

[0079] These organic phosphorus flame retardants can be used eitherindividually or as a combination of two or more thereof.

[0080] Organic phosphorus flame retardant (F) is added in an amount of0.1 to 30 parts by weight, preferably 0.2 to 25 parts by weight, stillpreferably 0.3 to 20 parts by weight, per 100 parts by weight of thetotal amount of polycarbonate resin (A) and aromatic polyester resin(B). If the amount of organic phosphorus flame retardant (F) is lessthan 0.1 part by weight, the effects in improving flame retardance andmolding processability are poor. If it exceeds 30 parts by weight, theresulting molded articles tend to have reduced impact resistance, heatresistance or solvent resistance.

[0081] In order to improve the impact strength, toughness, chemicalresistance and the like of the molded articles, it is preferable to add(G) one or more elastic resins selected from graft polymers and olefinresins. Elastic resins having at least one glass transition point at orbelow 0° C., particularly −20° C. or lower, are preferred for improvingthe impact strength.

[0082] Of elastic resins (G) the graft rubber is one comprising arubber-like elastomer to which a vinyl monomer is graft-copolymerized.

[0083] The rubber-like elastomers include diene rubbers, such aspolybutadiene, styrene-butadiene rubber, acrylonitrile-butadiene rubber,and alkyl (meth)acrylate-butadiene rubber, acrylic rubber,ethylene-propylene rubber, and siloxane rubber.

[0084] The vinyl monomer includes aromatic vinyl compounds, vinylcyanide compounds, alkyl (meth)acrylates, and other vinyl compoundscapable of being grafted to rubber-like elastomers.

[0085] The aromatic vinyl compounds include styrene, o-methylstyrene,m-methylstyrene, p-methylstyrene, α -methylstyrene, and vinyltoluene.

[0086] The vinyl cyanide compounds include acrylonitrile andmethacrylonitrile.

[0087] The alkyl (meth)acrylates include butyl acrylate, butylmethacrylate, ethyl acrylate, ethyl methacrylate, methyl acrylate, andmethyl methacrylate.

[0088] The other vinyl compounds include unsaturated acids, such asacrylic acid and methacrylic acid; glycidyl (meth)acrylates, such asglycidyl acrylate and glycidyl methacrylate; vinyl acetate, maleicanhydride, and N-phenylmaleimide.

[0089] The copolymerizing ratio of the rubber-like elastomer and thevinyl compound is not particularly limited. A preferred ratio forsecuring improvement in impact strength is 10/90 to 90/10, particularly30/70 to 80/20, by weight. If the weight ratio of the rubber-likeelastomer is less than 10, the effect in improving impact resistance islessened. If it exceeds 90, the graft rubber tends to have reducedcompatibility to resins (A) and (B).

[0090] Of elastic resin (G), the term “olefin resin” is used herein inits inclusive sense and is intended to include not only polyolefins inits narrow sense but also polydienes, mixtures of two or more of thepolyolefins and polydienes, copolymers comprising an olefin monomer andtwo or more diene monomers, copolymers comprising an olefin monomer andat least one vinyl monomer copolymerizable with an olefin, and the like.Examples of the olefin resins are homo- or copolymers comprising one ormore monomers selected from ethylene, propylene, 1-butene, 1-pentene,isobutene, butadiene, isoprene, phenylpropadiene, cyclopentadiene,1,5-norbornadiene, 1,3-cyclohexadiene, 1,4-cyclohexadiene,1,5-cyclooctadiene, 1,3-cyclooctadiene, α,ω-nonconjugated diene, etc.;and mixtures of two or more of these homopolymers and copolymers.Preferred among them are polyethylene and polypropylene from thestandpoint of improvement in chemical resistance of the resultingcomposition.

[0091] Copolymers comprising the above-described olefin component and avinyl monomer copolymerizable with the olefin, such as (meth)acrylicacid, an alkyl (meth)acrylate, glycidyl (meth)acrylate, vinyl acetate,maleic anhydride, N-phenylmaleimide, and carbon monoxide, are alsouseful. Examples of such copolymers are an ethylene-ethyl acrylatecopolymer, an ethylene-butyl acrylate-carbon monoxide terpolymer, anethylene-glycidyl methacrylate copolymer, an ethylene-glycidylmethacrylate-vinyl acetate copolymer, an ethylene-vinyl acetatecopolymer, an ethylene-vinyl acetate-carbon monoxide copolymer, anethylene-acrylic acid copolymer, an ethylene-maleic anhydride copolymer,and an ethylene-maleic anhydride-N-phenylmaleimide copolymer.

[0092] These polyolefin resins can be obtained by various polymerizationtechniques with no particular restriction. As for polyethylene, forinstance, high-density polyethylene, medium-density polyethylene,low-density polyethylene, linear low-density polyethylene, and the likeare produced depending on the polymerization process, any of them can beused for preference.

[0093] When the graft polymer and the olefin resin are used incombination as component (G), the above-mentioned various effects areenhanced.

[0094] The amount of elastic resin (G) to be added is preferably 0.1 to20 parts by weight, still preferably 0.1 to 15 parts by weight,particularly preferably 0.2 to 12 parts by weight, per 100 parts byweight of the total amount of polycarbonate resin (A) and thermoplasticpolyester resin (B). If it exceeds 20 parts, rigidity and heatresistance are reduced.

[0095] In order to further improve the heat resistance and mechanicalstrength of the resin, a reinforcing filler other than silicate compound(D) can be used either individually or in combination with component(D). Suitable inorganic reinforcing fillers include fibrousreinforcements, such as glass fiber, carbon fiber, and metal fiber;calcium carbonate, glass beads, glass powder, ceramic powder, metalpowder, and carbon black. They may be surface-treated to have increasedadhesion to the resin matrix. A silane coupling agent containing anepoxy group, such as epoxysilane, is a preferred surface treating agent,which will not reduce the physical properties of the resins. The surfacetreatment can be carried out in a conventional manner with no particularrestriction.

[0096] Two or more reinforcing fillers different in kind, particlediameter or length, manner of surface treatment, and the like can beused in combination.

[0097] The amount of the inorganic reinforcing fillers to be added isnot more than 100 parts by weight, preferably not more then 50 parts byweight, still preferably 10 parts by weight or less, per 100 parts byweight of the total amount of polycarbonate resin (A) and aromaticpolyester resin (B). Addition of more than 100 parts by weight not onlyresults in reduction of impact resistance but tends to reduce moldingprocessability and flame retardance. Moreover, as the amount of theinorganic reinforcing filler increases, there is a tendency todeterioration in surface properties and dimensional stability of theresulting molded articles. Where weight is put on these properties, itis preferred to minimize the amount of the inorganic reinforcing filler.

[0098] As long as the effects of the invention are not impaired, theflame-retardant resin composition according to the present invention cancontain arbitrarily selected additional thermoplastic or thermosettingresins, for example, liquid crystal polyester resins, polyester esterelastomeric resins, polyester ether elastomeric resins, polyolefinresins, polyamide resins, polystyrene resins, polyphenylene sulfideresins, polyphenylene ether resins, polyacetal resins, and polysulfoneresins, used either individually or as a combination of two or morethereof.

[0099] In order to further improve the performance of theflame-retardant resin composition of the invention, it is preferred touse antioxidants (e.g., phenol antioxidants and thioether antioxidants),heat stabilizers (e.g., phosphorus type stabilizers), and the likeeither individually or as a mixture of two or more thereof. If desired,the resin composition can contain one or more of other well-knownadditives, such as stabilizers, lubricants, parting agents,plasticizers, flame retardants other than phosphorus type compounds,flame retardation aids, ultraviolet absorbers, light stabilizers,pigments, dyes, antistatic agents, electric conductivity impartingagents, dispersants, compatibilizers, antimicrobials, and so on.

[0100] The method for preparing the flame-retardant resin composition ofthe invention is not particularly limited. For example, the compositionis prepared by drying the above-mentioned components and additives,resins, etc. and melt-kneading them in a melt-kneading machine, such asa single- or twin-screw extruder. Where a compounding ingredient isliquid, it can be added to the barrel of a twin-screw extruder by meansof a liquid feed pump.

[0101] The method for molding the thermoplastic resin compositionprepared in the present invention is not particularly limited. Moldingmethods customarily employed for thermoplastic resins, such as injectionmolding, blow molding, extrusion molding, vacuum forming, press molding,calendering, expansion molding, and the like, can be applied.

[0102] The flame-retardant thermoplastic resin composition of theinvention is suited to a variety of uses. Preferred uses includeinterior and exterior parts of appliances and office automationequipment, injection molded parts of automobiles, blow molded articles,extruded articles, expansion molded articles, etc.

BEST MODE FOR CARRYING OUT THE INVENTION

[0103] The present invention will now be illustrated in greater detailby way of Examples, but it should be understood that the presentinvention is not limited thereto. Unless otherwise noted, all the partsand percents are given by weight.

[0104] Evaluations of resin compositions were made in accordance withthe following methods.

[0105] Methods of Evaluation:

[0106] After the pellets obtained were dried at 120° C. for 4 hours, thedried pellets were injection molded by means of a 35t injection moldingmachine at a cylinder temperature of 280° C. and a mold temperature of70° C. to prepare a bar of 12 mm in width, 127 mm in length and 1.6 mm,2.5 mm or 6.4 mm in thickness and a plate of 150 mm×150 mm×2.5 mm (t).

[0107] 1) Flame Retardance (1.6 mm thickness)

[0108] The flame retardance of the 1.6 mm thick bar was rated on UL-94VStandard. An evaluation was done by judging at which of levels V-2, V-1and V-0 the flame retardance was.

[0109] 2) Flame Retardance (2.5 mm thickness)

[0110] The flame retardance of the 2.5 mm thick bar was rated on UL-94VStandard. An evaluation was done by judging at which of levels V-2, V-1and V-0 the flame retardance was. Further, a 2.5 mm thick bar and a 2.5mm thick plate were prepared from those resin compositions which wererated at V-0 in the above evaluation, and it was judged whether flameretardance was rated at 5VA or 5VB.

[0111] 3) Heat Resistance

[0112] Heat resistance was evaluated by measuring a deflectiontemperature under load on a 6.4 mm thick bar in accordance with ASTMD-648 under a load of 0.45 MPa.

[0113] 4) Long-term Heat Stability

[0114] A 6.4 mm thick bar was treated at 150° C. for 150 hours. Beforeand after the heat treatment, a flexural strength was measured inaccordance with ASTM D-790. A flexural strength retention (%) wascalculated from formula:

[0115] (Strength after treatment at 150° C.)/(Strength beforetreatment)×100

[0116] Some samples having poor heat resistance underwent considerabledeformation on heat treating at 150° C. so that the flexural strengthwas unmeasurable, which are indicated by—(hyphen) in Table 1.

[0117] 5) Smell

[0118] After being dried at 120° C. for 4 hours, the pellets were purgedfrom the cylinder of a 75t injection molding machine at a cylindertemperature of 300° C. The smell emitted then was evaluatedorganoleptically and graded as follows.

[0119] A . . . No smell

[0120] B . . . Little smell

[0121] C . . . Slight smell

[0122] D . . . Considerable smell

[0123] 6) Flowability

[0124] After the pellets were dried at 120° C. for 4 hours, a melt index(MI) was measured in accordance with JIS K6730 at 280° C. under a loadof 2160 g to evaluate the flowability.

EXAMPLE 1

[0125] Seventy-five parts of a bisphenol A type polycarbonate resin (A1)having a viscosity average molecular weight of about 22000, 25 parts ofa polyethylene terephthalate resin (B1) having an intrinsic viscosity ofabout 0.75 dl/g, 4 parts of Nova Excel 140 (C1) (a trade name of phenolresin-coated red phosphorus, produced by Rin Kagaku Kogyo K.K.), and 0.3part of Adeca Stab HP-10 (a trade name of a phosphite type stabilizer,produced by Asahi Denka Kogyo K.K.) were previously dry blended. Theblend was fed to the hopper of a vented twin-screw extruder with itscylinder temperature set at 280° C. (TEX 44, manufactured by The JapanSteel Works, Ltd.) and melt-extruded to obtain a resin compound. Theresults of evaluations on the resulting resin composition are shown inTable 1.

EXAMPLES 2 TO 26

[0126] Resin compositions were prepared in the same manner as in Example1, except for changing the compounding ingredients as shown in Tables 1and 2. When the total amount of silicate compound(s) (D) exceeded 10parts, component (D) was added through the side feed opening of theextruder. Of organic phosphorus flame retardants (F), those which areliquid at room temperature were fed to the cylinder barrel by means of aliquid feed pump. The compounding ingredients used were as follows. Theresults of evaluations are shown in Tables 1 and 2.

[0127] (A) Polycarbonate Resin

[0128] (A2) Bisphenol A type polycarbonate resin having a viscosityaverage molecular weight of about 28800.

[0129] (B) Thermoplastic Polyester Resin

[0130] (B2) Polyethylene terephthalate resin having an intrinsicviscosity of 0.6 dl/g.

[0131] (B3) Polybutylene terephthalate resin having an intrinsicviscosity of 0.85 dl/g.

[0132] (C) Stabilized Red Phosphorus

[0133] (C2) Stabilized red phosphorus having an average particlediameter of 20 μm, having been coated with 10% of aluminum hydroxide.

[0134] (D) Silicate Compound

[0135] (D1) Mica (A-21S, a trade name, produced by Yamaguchi Unmo K.K.)

[0136] (D2) Talc (Microace K-1, a trade name, produced by Nippon talcK.K.)

[0137] (E) Fluorocarbon resin and/or Silicone

[0138] (E1) Polytetrafluoroethylene (Polyfureon FA-500, a trade name,produced by Daikin Industries, Ltd.)

[0139] (E2) Silicone (Si Powder DC4-7051, a trade name, produced byToray Dow Corning Silicone Co., Ltd.)

[0140] (F) Organic Phosphorus Flame Retardant

[0141] (F1) Triphenyl phosphate

[0142] (F2) Bisphenol A bis(dicresyl) phosphate

[0143] (F3) Resorcinolbis(di-2,6 -xylyl) phosphate

[0144] (F4) Hydroquinonebis(di-2,6-xylyl) phosphate

[0145] (F5) Resorcinolbis(diphenyl) phosphate

[0146] (G) Elastic Resin (selected from graft polymers and olefinresins)

[0147] (G1) MBS resin (Kane Ace M-511, a trade name, produced byKanegafuchi Chemical Industry Co., Ltd.)

[0148] (G2) Linear low-density polyethylene (LLDPE) (IdemitsuPolyethylene-L 0134N, a trade name, produced by Idemitsu PetrochemicalCo., Ltd.)

[0149] (G3) Ethylene-ethyl acrylate copolymer (Evaflex EEA A-713, atrade name, produced by Du Pont-Mitui Polychemicals Co., Ltd.)

[0150] Other Additives

[0151] Glass fiber (T-195H/PS, a trade name, produced by Nippon ElectricGlass Co., Ltd.)

COMPARATIVE EXAMPLES 1 TO 9

[0152] Resin compositions were prepared in the same manner as in Example1, except for changing the compounding ingredients as shown in Table 3below. The results of evaluations are also shown in Table 3.

[0153] The following resins were used as comparative resins other thanthe polycarbonate resins and polyester resins. PPE Resin:Poly(2,6-dimethyl-1,4-phenylene)ether resin having a limiting viscositynumber of 0.50 as measured in chloroform at 30° C.

[0154] HIPS Resin: Rubber-modified high impact polystyrene (Estyrene HIH-65, a trade name, produced by Nippon Steel Chemical Co., Ltd.)

[0155] Red Phosphorus: Untreated red phosphorus (reagent) was used forcomparison with stabilized red phosphorus. TABLE 1 Example No. ResinComposition 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 A PC (A1) 75 75 75 75 7585 75 75 75 60 80 80 75 80 PC (A2) 75 B PET (B1) 25 25 25 25 15 25 25 2540 20 20 25 20 PET (B2) 25 PBT (B3) 25 C Stabilized 4.0 5.0 0.7 3.0 0.70.4 0.7 0.6 1.0 0.5 2.0 1.5 0.3 0.2 red P (C1) Stabilized 1.0 red P (C2)D Mica (D1) 3.0 15 3.0 3.0 3.0 10 0 5 15 15 Talc (D2) 3.0 15 5 5 E PTFE(E1) 0.1 0.3 0.3 0.3 0.3 0.1 0.3 0.5 0.8 0.5 Silicone (E2) 1.0 G MBS(G1) 1 1 1 0.5 LLDPE (G2) EEA (G3) 3 3 3 2 Others Glass fiber 5 5 HP-100.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.5 0.5 (stabilizer)Flame retardance at V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0 V-0V-0 V-1 1.6 mm (t) (UL-94) Flame retardance at V-0 V-0 V-0 V-0 V-0 5VB5VB 5VB 5VB 5VA 5VA 5VA 5VA 5VA V-0 2.5 mm (t) (UL-94) Heat resistance(° C.) 144 130 139 145 139 138 135 137 138 145 146 147 145 145 147Long-term heat 118 102 108 120 108 105 106 107 102 117 120 120 110 118110 stability (%) Flowability (g/10 min) 15 15 14 8 14 11 11 12 14 9 7 77 8 6 Smell B B A A A A A A A A A A A A A

[0156] TABLE 2 Example No. Resin Composition 16 17 18 19 20 21 22 23 2425 26 A PC (A1) 90 85 90 80 90 90 80 PC (A2) 85 70 85 75 B PET (B1) 1010 20 10 15 10 20 PET (B2) 15 30 25 PBT (B3) 15 C Stabilized red P (C1)1 1 0.8 1 1.5 2.5 1 1 0.6 1 1.5 D Mica (D1) 3.0 3.0 3.0 3.0 3.0 3.0 3.015 10 10 Talc (D2) 5 E PTFE (E1) 0.5 0.5 0.5 0.5 0.5 0.5 0.2 0.5 0.5 0.2F Phosphorus compound (F1) 6 Phosphorus compound (F2) 5 4 4 6 5 5 7Phosphorus compound (F3) 6 Phosphorus compound (F4) 4 Phosphoruscompound (F5) 6 Others HP-10 (stabilizer) 0.2 0.2 0.2 0.2 0.2 0.2 0.20.2 0.2 0.2 0.2 Flame retardance at 1.6 mm (t) V-0 V-0 V-0 V-0 V-0 V-0V-0 V-0 V-0 V-0 V-0 (UL-94) Flame retardance at 2.5 mm (t) V-0 5VB 5VB5VB 5VB 5VB 5VB 5VB 5VA 5VA 5VA (UL-94) Heat resistance (° C.) 118 121123 122 121 119 120 118 133 133 131 Long-term heat stability (%) 85 9995 91 99 93 92 94 98 106 103 Flowability (g/10 min) 18 18 19 17 20 23 1819 10 14 13 Smell A A A A A A A A A A A

[0157] TABLE 3 Comparative Example No. Ref. Resin Composition 1 2 3* 4 56 7 8 9 Ex. 1 A PC (A1) 100 100 75 75 60 75 70 B PET (B1) 100 25 25 4025 30 Other PPE 25 25 resins HIPS 75 75 C Stabilized red P 4.0 2.0 5.015.0 6.0 (C1) Untreated red P 0.6 D Talc (D2) 15 3.0 E PTFE (E1) 0.1 0.10.1 0.1 0.1 0.3 0.2 0.2 0.2 F Phosphorus 5.5 compound (F5) G MBS (G1) 15 EEA (G3) 2 3 Others Stabilizer (HP-10) 0.3 0.3 0.3 0.3 0.3 0.3 0.3Glass fiber 50 Flame retardance at 1.6 mm V-0 V-0 V-1 V-0 not not V V-0V-0 not V not V (t) (UL-94) V** Flame retardance at 2.5 mm V-0 V-0 V-15VA not V not V V-0 V-0 V-0 V-0 (t) (UL-94) Heat resistance (° C.) 136135 220 140 135 138 137 110 105 108 Long-term heat stability (%) — — 100113 95 93 98 — — — Flowability (g/10 min) 5 4 8 10 15 7 14 22 15 18Smell B A B D A A D B D A

[0158] Containing no polyester resin, Comparative Examples 1 and 2 havepoor flowability and enjoy no improvements in long-term heat stabilityand heat resistance even with addition of red phosphorus. ComparativeExample 3, which contains no polycarbonate resin, is inferior in flameretardance. Comparative Example 4 gives off smell on account of thepresence of a large amount of stabilized red phosphorus. ComparativeExamples 5 and 6 have poor flame retardance in the absence of stabilizedred phosphorus. Besides, Comparative Examples 5 and 6 are inferior toExamples 5 and 10, respectively, in heat resistance and long-term heatstability. Comparative Example 7 produces smell because of the use ofnon-stabilized red phosphorus. Only using the organic phosphorus flameretardant, Comparative Example 8 exhibits poor heat resistance and poorlong-term heat stability. Compared with Reference Example 1, ComparativeExample 9 shows no improvements in flame retardance, heat resistance,and long-term heat stability in spite of the addition of stabilized redphosphorus. This proves that the effects of stabilized red phosphorus onthese characteristics can never be manifested except when added tospecific resins.

[0159] As is clear from the foregoing, it is seen that all thecompositions according to the present invention are excellent in heatresistance, long-term heat stability, flame retardance and freedom fromsmell as well as flowability in molding. It is also seen that theseeffects cannot be obtained when stabilized red phosphorus is added toresins other than those specified in the present invention.

[0160] Industrial Applicability

[0161] The present invention provides a flame-retardant resincomposition exhibiting excellent characteristics in flowability inmolding, heat resistance, long-term heat stability, flame retardance,and smell, which are of great use in industry.

1. A flame-retardant thermoplastic resin composition comprising (A) 50to 95 parts by weight of a polycarbonate resin, (B) 5 to 50 parts byweight of a thermoplastic polyester resin, and (C) 0.1 to 5 parts byweight, per 100 parts by weight of the total amount of (A) and (B), ofcoated stabilized red phosphorus.
 2. A flame-retardant thermoplasticresin composition according to claim 1 , wherein the composition furthercontains (D) 0.1 to 100 parts by weight of a silicate compound per 100parts by weight of the total amount of (A) and (B).
 3. A flame-retardantthermoplastic resin composition according to claim 1 , wherein thecomposition further contains (E) 0.01 to 5 parts by weight of afluorocarbon resin and/or silicone per 100 parts by weight of the totalamount of (A) and (B).
 4. A flame-retardant thermoplastic resincomposition according to any one of claims 1 to 3 , wherein the coatedstabilized red phosphorus (C) is present in an amount of 0.1 to 3 partsby weight, the silicate compound (D) is present in an amount of 0.1 to100 parts by weight, and the fluorocarbon resin and/or silicone (E) ispresent in an amount of 0.01 to 5 parts by weight.
 5. A flame-retardantthermoplastic resin composition according to any one of claims 1 to 4 ,wherein the composition further contains (F) 0.1 to 30 parts by weightof an organic phosphorus flame retardant per 100 parts by weight of thetotal amount of (A) and (B).
 6. A flame-retardant thermoplastic resincomposition according to any one of claims 1 to 5 , wherein the organicphosphorus flame retardant (F) is a phosphoric ester represented byformula:

wherein R¹, R², R³, and R⁴ each represent a monovalent aromatic oraliphatic group; R⁵ represents a divalent aromatic group; n represents anumber of from 0 to 16; nR³'s and nR⁵'s each may be the same ordifferent.
 7. A flame-retardant thermoplastic resin compositionaccording to any one of claims 1 to 6 , wherein the composition furthercontains (G) 0.1 to 20 parts by weight of at least one elastic resinselected from a graft polymer and an olefin resin per 100 parts byweight of the total amount of (A) and (B).
 8. A flame-retardantthermoplastic resin composition according to any one of claims 1 to 7 ,wherein the thermoplastic polyester resin (B) is a polyalkyleneterephthalate having an alkylene terephthalate unit content of not lessthan 80% by weight.
 9. A flame-retardant thermoplastic resin compositionaccording to any one of claims 1 to 8 , wherein the coated stabilizedred phosphorus (C) is red phosphorus coated with at least one substanceselected from a thermosetting resin, a metal hydroxide, and a platingmetal.